OSRAM Presents An Ambient Light Sensor With A Digital I˛C Output

Small, digital and extremely economical

The SFH 5712 from OSRAM Opto Semiconductors detects ambient
brightness in the same way as the human eye, and is the only sensor
on the market that offers not only standard data rates but also high
speed rates of up to 3.4 MHz. Without the need for any additional
control commands, an integrated circuit in the sensor automatically
provides a measured value between 3 and 65,000 lx twice a second.
The sensor has only four connections and takes up very little space,
measuring just 2 x 2 x 0.7 mm. It can be easily controlled via its
integrated I˛C interface.

“The benefits of our digital ambient light sensor are obvious”, said
Dr. Werner Kuhlmann, Development Manager for Silicon Detectors at
OSRAM Opto Semiconductors. “The sensor digitally transmits the true
lux value so there is no need for complicated formulas to calculate
an appropriate value from the output signal. This saves one
operation in the application. It is also insensitive to mains-power
related 50-60 Hz flickering that is produced for example by
fluorescent lamps.” With 150 µA during operation and only 1.5 µA in
stand-by mode the sensor consumes very little power.

The SFH 5712 is primarily intended for mobile applications in which
the brightness of the display is constantly adjusted according to
available ambient light. This extends the interval between recharges
and therefore improves the service life of the devices. The main
beneficiaries are cell phones, PDAs, navigation devices, netbooks
and laptops. Ambient light adjusted brightness also improves
readability.
A good legible display on satellite navigation devices is not just
highly convenient but also an important safety aspect.

OSRAM has added the first digital ambient light sensor to its
product portfolio so it can now offer the right sensor for a wide
range of requirements and for every area of application